It has been recognized that an electrical toothbrush is more effective in removing plaque and preventing gum disease than a conventional manual toothbrush. It is also well known that the manual squeezing action of dentifrice dispensing presents a significant challenge to severe arthritis suffers who lack finger dexterity and strength. Thus a total-electrical toothbrush is desirable for everyday dental care and a necessity for the physically challenged. Oral hygiene requires that toothbrush bristles should be replaced on a regular basis for maintaining bristle effectiveness and minimizing bacteria buildup. While the entire toothbrush can be replaced, it is desirable to discard only the part having bristles and retain the drive mechanism and the brush handle as permanent parts for minimizing the replacement costs. For long service life of the permanent parts, all wearable parts need to be included in one replacement unit. For the ease of replacement, it is desirable to have a replaceable snap-on bristle unit for fastening on a permanent drive head containing driving components. For the convenience of portability, it is desirable to have a self-contained, dentifrice dispensing electrical toothbrush for brushing anywhere at anytime. For the ease of operation especially for the physically challenged, it is desirable simply to press on an electrical switch for the automatic dispensing of dentifrice material to the top of the bristles. The objects of this invention are to achieve all of the above desirable features in one electrical toothbrush.
(1) Field of the Invention
The present invention relates to electrical dentifrice dispensing toothbrushes with a replaceable bristle unit.
(2) Prior Art
It is recognized in the prior art that electrical toothbrushes which have oscillatory brush elements are more effective than toothbrushes with rotating brush heads. The reciprocating movement and wiping action of the bristles provides an effective means for plaque removal. U.S. Pat. No. 4,326,314 by Moret and Jousson describes a means for oscillating a brush head through an oscillating shaft which is connected to a cam riding on a biased wheel mounted on the shaft of a motor. Since the source of vibration is at the cam and the motor which is usually located in the handle, a strong vibration may cause discomfort during brushing.
To minimize the vibration at the handle, U.S. Pat. No. 5,625,916 by McDougall provides a means for converting rotary motion to oscillatory motion near the brush head area which is remote to the motor. It uses a bent remote-most end of a shaft having rotary motion to engage with a slot formed on the side of a bristle holder to force it to oscillate back and forth as the bent remote-most end is driven in a circular annular path. While it achieves relocation of the vibration source to the brush head, the central axis of the bent remote-most end is required to intersect with the central axis of the brush head. This requirement precludes its application from simultaneously driving two brush heads since the same central axis of the remote-most end of a shaft cannot intersect two separate central axes in its circling positions. Also, its use of a closed ended slot on the side of the brush head for engagement also prevents the remote-most end from reaching more than one brush head.
Owing to its complex assembly, the entire neck including the brush head, the mounting base and the drive shaft assembly are replaced when the brush head is changed.
U.S. Pat. No. 5,784,743 by Shek uses an off-set finger mounted at the end of a rotating shaft for engaging the fork of a pivotally supported wobble plate which is meshed with a gear for oscillating a brush head. The use of the closed end fork and the blocking of the extension of the finger by the pivoting and gear-meshing mechanism prohibit its application to oscillate two brush heads. Similarly, the replacement of the whole neck including the drive shaft is required when the brush head is replaced.
The prior art has also recognized that the brushing area is broadened and the brushing time reduced when two brush heads are used instead of one. For oscillating two brush heads, U.S. Pat. No. 5,353,460 by Bauman uses an oscillating shaft to drive one brush head and utilizes a linkage between the two brush heads to drive the other brush head. The linkage requires a pivoting post on each brush head which adds an increased friction load to the drive mechanism for oscillation of the brush heads. U.S. Pat. No. 5,099,536 by Hirabayashi uses two shafts aligned at different angles. The gearing mechanism allows for driving more than one brush head but its drive mechanism does not cause oscillatory motion. In order to change the brush head, each of the above two patents also requires replacing the neck connected to the brush head which includes part of a drive shaft assembly.
A description of an electrical toothbrush which dispenses liquid is provided in U.S. Pat. No. 5,321,866 by Klupt. The patent discloses a delivery means for a cleaning liquid through oscillating brush heads. A motor is connected to a series of gear mechanisms causing a drive shaft to oscillate and a piston to pump the liquid through a flow conduit to openings in the brush head. Because it is connected to the same motor, the motorized piston pumps the liquid continuously while the brush heads are oscillating. This common drive mechanism is not desirable for dispensing material that only needs to be dispensed prior to the brushing action.
A dentifrice dispensing electric toothbrush of U.S. patent application Ser. No. 09/649,074 by Kuo mounts a pair of rotary bristle elements on a pair of posts attached to a brush head and uses a retention cradle for keeping the two rotary bristle elements in free-to-rotate positions. The neck of the toothbrush includes a channel which is part of the flow path for dentifrice material that is pumped from the cartridge to the brush head. The pumping is achieved by using an elastic compressible button positioned on the external surface of the brush handle for manually supplying a pumping force to pump dentifrice and for simultaneously activating a switch positioned inside the brush handle to energize the motor. Although only the bristle elements and the retention cradle are replaced, the posts which are subject to wear from the oscillation motion remain on the brush head. A worn post can cause wobbling of oscillating bristle element and noise that results in reduced service life of the toothbrush. Also, catch arms used in the retention cradle are only for keeping the bristle elements in place in packaging, not required in the operation of the toothbrush. Furthermore, the elevated position of the cradle platform from the bristle base is a barrier for the free brushing motion and running of cleaning water. As for dentifrice dispensing, the requirement of manual squeezing on the compressible button on the handle is a major hindrance for a severe arthritis suffers who lack of finger dexterity and strength.
In view of the deficiencies as exemplified in above patents in the prior art, there is a pressing need for an electrical dentifrice dispensing toothbrush that can provide permanent drive head and handle with minimal replacement of bristle parts, and a pumping means that does not require manual squeezing action for dispensing the dentifrice material.
This invention provides an electrical toothbrush that satisfies the needs for less throw-away, easy replacement of bristle elements and high cleaning efficiency. It also provides an electrical means of dispensing dentifrice material from a cartridge attached to the brush head for the convenience of users in general and especially for severe arthritis sufferers who have difficulty in the manual squeezing action of dispensing toothpaste. The replaceable bristle unit which is mounted on a permanent drive head consists of a rotary bristle element, a staionary bristle element, and a detachable snap-on platform which has a post for supporting the free-rotation of the rotary bristle element. The mounting of the rotary bristle element on the post is un-detachable as detachment is prevented by the engagement of the annular groove in the bushing of the bristle element and the protruding rim of the post with 90 degree detent angle. All the wearable parts are included in the replaceable bristle unit and the driver components, including the drive shaft, remain in the permanent drive head and the body of the electrical toothbrush. The replaceable bristle unit is locked to the drive head through the engagement of its latch arms with the latch recesses on the side walls of the drive head. The latch arms are released for replacing the bristle unit by applying an opposing force on the tabs that are on the opposite ends of the latch arms which are hinged on the edges of the detachable platform. The tabs are optionally layered with rubber material and positioned below the bristle surface and for protecting gums from excessive brushing pressure. The replaceable bristle unit of present invention may have two rotary bristle elements or a combination of a rotary and a stationary bristle element. For achieving the use of the minimal disposal bristle unit with a compact drive head, the present invention optionally employs an oscillation conversion linkage for converting the rotational motion of a drive shaft at the input end to a planar oscillation in the output end for driving the rotary bristle element. The planar oscillation motion reduces the height requirement (in the bristle direction) for the drive head.
The present invention also includes an electrical dentifrice dispensing toothbrush which uses a replaceable bristle unit and an electrical means of delivering dentifrice material from a cartridge in the handle to the top of bristles. To achieve these functions, the detachable platform of the replaceable bristle unit has an opening for slidably mounted on the wall of a spout opening extending from the top of the drive head. The delivery of the dentifrice material is achieved by using a toothbrush neck having two separated channels. One channel houses the drive shaft and the other channel functions as part of the flow path for the dentifrice material as it is pumped from the handle to the brush head. The electrical pumping mechanism includes a switch, a rotary solenoid, and a plunger in contact with a resilient compressible button. The activation of the switch causes the rotary solenoid to move the plunger to press on the resilient compressible button for applying pressure to force dentifrice material to flow to the top of the bristles. Through a control mechanism, release of the switch causes the rotary solenoid, the plunger, and the elastic button back to their original home positions and accordingly the follower inside the cartridge advances to keep the dentifrice material inside the cartridge at a packed condition for next pumping action.
The replaceable bristle unit of present invention is applicable to dual rotary bristle elements, a combination of rotary and stationary bristle elements, or a combination of rotary and dentifrice dispensing bristle elements.
The essential components of the electrical toothbrush include 1) a handle which serves as a housing for a motor, batteries and a cartridge containing dentifrice material; 2) a replaceable bristle unit having a rotary bristle element with a drive notch and a detachable platform having latch arms; 3) a drive head having a driver component that engages with the drive notch of the bristle element and latch recesses on its side walls for locking with the latch arms of the detachable platform; 4) a neck which connects the handle and the drive head; 5) a drive mechanism that is driven by a motor and imparts an oscillatory motion to the driver component in the drive head. The electrical dentifrice dispensing toothbrush also includes; 6) a series of flow path components including a spout in the drive head, a flow channel in the neck, a pump chamber, a one-way valve and an internal resilient compressible button; 7) an electrical actuation mechanism including a switch, a rotary solenoid, and a plunger which presses on the resilient compressible button for dispensing the dentifrice material when the switch is actuated; 8) a refillable dentifrice cartridge.